This invention relates to a thin film magnetic head which is applied to magnetic disc storage. More particularly, it relates to a thin film magnetic head used for reproducing.
With improving the high recording density of an HDD (Hard Disk Drive), a thin film magnetic head mounted in it requires even narrower track width, narrower gap length, and higher sensitivity. At present, a thin film magnetic head is used by combining a write head with a read head. A GMR head applying the GMR effect is mainly used for the read head. This GMR head is a CIP (Current In Plane) type head in which an electric signal flows parallel in the film surface of a sensor film. For further improvement of the recording density in the future, a TMR (Tunneling MagnetoResistive effect) head and a CPP-GMR (Current Perpendicular to a Plane-Giant MagnetoResistive effect) head have been actively developed, which are understood to have advantages of narrow track width and narrow gap length. This TMR head and CPP-GMR head are not CIP type heads in which an electric signal flows parallel in the film surface of a sensor film, but CPP type heads in which flow is perpendicular to the film surface, which is different from a conventional GMR head.
JP-A No. 280635/2002 disclosed that, for a TMR head, improvement of the barrier layer of a TMR sensor film improved the insulation, developer resistance, smoothness, and heat radiation. JP-A No. 198000/2003 disclosed that, for a CPP-GMR head, the alignment margin was improved by making the lower electrode connected to the sensor film in a convex shape and making the width of the upper electrode connected to the sensor film smaller than the lower electrode. JP-A No. 298144/2003 disclosed that planarizing the convex shaped part made it possible to form a more uniform sensor film, resulting in improved characteristics.